Microphone preamplifiers

TABLE OF CONTENTS

1。预应力混凝土
2。Classical Preamplifiers
3。CCLD Preamplifiers
4。选择器，选择器
5。Preamplifier Type

 

PREAMPPLIFIERS FOR CONDENSER MICROPHONES

A condenser microphone must be combined with a preamplifier to provide impedance conversion，some filtering，and the capability to drive relatively long cables without significant signal degradation。

Our preamplifiers are designed in accordance with two principles，referred to as Classical Preamplifiers，and CCLD Preamplifiers.Each provide their own special set of features:

CLASSICAL PREAMPIFIERS

The classical preamplifier has an easy to understand concept.It is basically aunity gain amplifier with extremely high input impedance and very low input capacitance。 

• The supply voltage can be either±15V DC or a single80V DC。
• The output signal has its own separate wire，as do the polarization and CIC voltage。
• Pin5is often used for transmission of TEDS data（so called Class II TEDS）。
• Charge Injection Calibration（CIC）is performed by injecting a signal on pin1of the LEMO connector。

CCLD Preamplifiers

Despite its origin in the vibration transducer world，the Constant Current Line Drive（CCLD）principle is increasing in popularity in the area of sound and measurement applications。Different manufacturers market transducers using the CCLD principle under different names。

The benefit of CCLD is that the same wire is used for both the signal and the supply current.Using TEDS Class I even the TEDS data can be transmitted over that same wire（using a level controlled electronic switch as shown in the figure below）。 

 

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Classical vs.CCLD Preamplifier

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SELECTING A MICROPHONE PREAmpPLIFIER

Brüel&Kjér offer large selection of robust and acoustically optimised preamplifiers that allow operation in awide range of environmental conditions。Brüel&Kjér preamplifiers allows the use of extremely long cables，even with high sound pressure levels present at high frequencies。

• Preamplifiers are available in1/2-inch and 1/4-inch dimensions，directly fittting with the most used cartridge sizes。
• Adaptors1英寸和1/8英寸微动支架
• The most popular classical1/2-inch preamplifier is Type2669.Avalable in several different versions。
• Type2669 combines a CCLD preamplifier and an A-weighting filter in a single unit.The preamplifier is easily distinguished due to the two engraved rings
• When insert voltage calibration is required，Type2673is the obvious choice。
• Type2695，maybe due to its small size，（half the length of the extremely popular CCLD preamplifier Type 2671），不合格单位

A CCLD input can be connected to both microphones and vibration sensors（and many other sensors with CCLD output）。Due to the working principle the signal is superimposed on a DC voltage.This DC bias voltage is typically around12V.Bias drift（over temperature or time）will reduce the dynamic range。

typically20-28V DC compliance voltage out of the front-end），there is some limitation in the upper limit for a CCLD solution.Another limitation of CCLD solution is that only prepolarized microphones can be used and that CIC is not available。

This，however，in many practical applications is happily accepted to reap the benefits of CCLD:Ease of use and cheap cables！
 

PREAMPPLIFIER TYPES AND APPLICATIONS

*Acoustical means a tapered preamplifier house。Other preamplifiers have cylindrical houses

 

WANT TO KNOW MORE？

For further details of the range，availability，and price，please use the link below to get in touch with your local Brüel&Kjér representative。